Adolescent girls in the United States are putting on weight
because they are doing less physical activity than they
did as children, according to a study released.
Research by scientists at the University of New Mexico
in Albuquerque showed that increasing exercise to the equivalent
of 2-5 hours of brisk walking each week could help to prevent
girls from gaining 4-9 kilos (9-20 lbs) during their teens.
"Preventing the steep decline in activity during adolescence
is an important method to reduce obesity," Sue YS Kimm,
the lead researcher, said in a study published online by
The Lancet medical journal.
Over 9 million young people in the United States aged 6-19,
or 16 percent, are considered overweight, according to the
Centers for Disease Control (CDC)
in Atlanta, Georgia.
Obesity is by measured by body mass index (BMI). It is
calculated by dividing weight in kilograms by height in
meters squared. A BMI of more than 25 is considered overweight.
More than 30 is obese.
Kimm and her team studied the BMI and changes in physical
activity in more than 2,200 girls from three U.S. cities
who were followed up from the ages of 9 to 19. They also
measured their skin folds, which is another indication of
being overweight and obese.
The girls filled in a questionnaire about their physical
activity and eating habits.
Although what they ate did not change, the researchers
said there was a doubling in the rate of excess weight and
obesity in girls who had a pronounced decline in physical
activity during the transition from childhood to adolescence.
"Black girls were significantly heavier and fatter than
white girls throughout adolescence, with increasing racial
differences with age," Kimm said in the journal.
In the study about 32 percent of white girls kept up their
childhood level of physical activity in adolescence, compared
to 11 percent of the black girls.
"In view of the global obesity epidemic, maintenance of
modest amounts of activity during adolescence could be a
method for primary prevention of obesity development and
adult-onset chronic diseases," Kim added.
Obesity increases the risk of other illnesses including
Type 2 diabetes and heart disease.
